Spark-plug tester



E. BORDAHL.

SPARK PLUG TESTER.

APPLICATION men M,AY1B.I918.

1,330, 1 61 Patented Feb. 10, 1920.

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SPARK-PLUG TESTER.

Specification of Letters Patent. Patented Feb. 11), 1920.

Application filed May 18, 1918. Serial No. 235,311.

To all whom it may concern:

Be it known that I, EVEN BORDAIIL, a citizen of the United States, residing at Roslyn, in the county of Day and State of South Dakota, have invented certain new and useful Improvements in Spark-Plug Testers, of which the following is a specification.

This invention relates to a spark plug tester and has for its object to provide a electric current therethrough, t0 visibly dis-v close the condition of the plug as to Whether it is in perfect condition, permanently disabled, intermittently inoperative, or has other defects.

With these objects in view, together with others which will appear as the description proceeds, the invention resides in the novel formation, combination and arrangement of parts, all as will be described more fully hereinafter, particularly pointed out in the claim and illustrated in the accompanying drawings, in which,

Figure 1 is an elevation of the improved spark plug tester.

Fig. 2 is a longitudinal sectional view of the same, and,

Fig. 3 is a cross sectional view on the line 3-3 of Fig. 2.

In the drawings 10 indicates-the casing of the instrument made from non-conducting material, preferably glass, of tubular form and of a diameter that will readily permit the same t0 be carried in the pocket. On the ends of the casing 10 are fitted caps 11- and 12 which are cemented in place.

From the end of cap 11 there projects a threaded stem 13 on which is fitted a thumb nut 14, these parts forming a binding post for the attachment of an electric circuit wire 15 from a battery, not shown. A similar post may be mounted on the cap 12, or the same may be left Without projection, butv preferably a plate or loop 16 extends from the end of the cap through which is formed a perforation 17 to be fitted and secured on the binding post 18 of the spark plug 19 when the latter is to be tested.

Within the bore of the casing 10 is mounted a Geissler or vacuum tube 20 of the usual form containing some special gas or rarefied a r, the ends of \VlllCll tube are sealed as shown around platinum 'wires 21 and- 22 that project a short distance within the ends of the tube, a space being left between them to form a spark jump which when in use becomes illuminated by the passing current of electricity and so indicates to the eye the condition of the spark plug 19'. The outer ends of the platinumwires 21 and 22 are soldered or otherwise connected to the re-- spective caps 11 and 12. The ends of the Geissler tube 20 are held in place within the casing by cement 23 which holds the tube rigidly in the axis of the casing.

In using the instrument, the circuit wire is disconnected from the spark plug to be tested and theloop 16 attached to the binding post of said plug. The circuit wire is then connected to the binding post of the instrument as at 15, Fig. 1. If now, the electric circuit be closed, the Geissler tube will become brightly illuminated should the spark plug be in perfect condition. If, however, the spark plug be defective,-no illumination of the Geissler tube will take place.

i If the test be made while the engine is running, the regular intermittent illumination of the tester will show that the plug is in perfect working condition, but an irregular illumination of the tester or no illumination at all will indicate a defective spark plug. 7

The tester may be applied in turn to each spark plug, or by using a separate tester for each plug, the condition of the entire series of spark plugs may be indicated and compared at a glance. Instead of connecting the loop 16 to the binding post of the spark plug, it maybe simply placed in contact therewith, or 1f the cap 12 is not provided with a loop, the cap itself may be placed against the spark plug. Instead of making the casing 10 of a glass tube, hard rubber, vulcanite, or other non-conducting material may be employed, but with these opaque substances, it will be necessary to make a longitudinal slot in the side of the casing through which the Geissler tube 20 maybe observed.

The foregoing description and the drawings have reference to what may be considered the preferred, or approved form of my invention. It is to be understood that I may make such changes in construction and arrangement and combination of parts,

materials, dimensions, et cetera, as may prove expedient and fall within the scope of the appended claim.

Having thus fully described my invention, what I claim as new and desire to secure 7 by Letters Patent, is:

In a device of the character described, the combination of a reduced hollow protector casing, a vacuum tube positioned within the hollow casing and being spaced from the inner surfaces thereof, caps fitted over the ends of said casing for constituting seals, wires carried by said caps and extending concentrically within the casing to project through the ends of said vacuum tube to the 15 same time holding said Wires and caps 20 against displacement, and attaching means on the exterior surfaces of said caps.

In testimony whereof I affix my signature in presence of two witnesses.

EVEN BORDAHL. \Vitnesses:

S. K. STIANSON, ANDREW SWANSON. 

